According to Kant, the rational agent should not only know what is right,...
but should also be motivated to act by feelings of empathy, sympathy and the good feeling that doing the right thing brings.
This statement is not true. To Kant, the only proper reason for acting in some certain way is because that action is a person's duty. The only thing that should (not does) motivate a person to act is that person's desire to do his or her duty.
Kant does not believe that human beings should be motivated by a desire to feel good. His thinking is almost the opposite of this. People, to Kant, are not supposed to act out of emotion or any sort of feeling. Instead, they are supposed to act on their duty, as revealed to them through their reason. They are supposed to use their reason to figure out what they should do (using the categorical imperative, for example) and act as they should because it is their duty to do so.